Neber-Bössel synthesis

What is Neber-Bössel synthesis?

The Neber-Bössel synthesis, which involves the transformation of o-amino mandelic acid into 3-hydroxy-cinnoline, was initially reported in 1929 by Bössel, who was a student of Neber. Subsequently, Neber et al. extended this reaction.

Neber-Bössel synthesis - general reaction scheme
Neber-Bössel synthesis

= H, Me, Cl, etc.
The Neber-Bössel synthesis comprises of three key steps: diazotization of o-amino mandelic acid, reduction using stannous chloride SnCl2, and acidic cyclization with hydrochloric acid HCl.


  • Bössel, G., Chem. Zentr., 1929, 100, 3015
  • Neber, P. W.; Knoller, G.; Herbst, K. and Trissler, A., Ann., 1929, 471, 113